1. Field of the Invention
The present invention relates to an image reading apparatus, an image reading method and a memory medium therefor.
2. Related Background Art
In the conventional image processing apparatus, there is already known a printer which receives data from a computer and forms a record on a recording sheet with a recording head, based on thus received data. Such printer is recently provided with not only the recording function but also a function of reading the image data on an original with a scanner unit. Such image processing apparatus is so constructed as to execute both the recording function and the original reading function by mounting a recording head or a scanner unit on a carriage and utilizing the recording sheet transporting system for both functions. Thus, in such image processing apparatus, the recording function is achieved by detachably mounting a recording head of dot impact type, thermal transfer type or ink jet type on the carriage and moving such recording head by moving means along the recording sheet, while the reading function is achieved by replacing the recording head with a scanner unit on the carriage and moving the scanner unit along the original.
The conventional original reading with such scanner unit is executed in one pass for each reading band with a green light source in case of a monochromatic scanner unit, and, in case of a full-color scanner unit, the reading is executed in succession with red, green and blue light sources. After the reading of one band, the original is advanced by the width of the band, and the above-explained operation is repeated until a reading area requested by the user is covered.
However, such conventional original reading method has been associated with insufficient image quality, because of so-called bandwise fluctuation, resulting from the matching error with the reference data caused by a fluctuation in the distance between the original and the scanner. The optical system constituting the inexpensive reading means such as th canner mentioned above can only be constituted with inexpensive lenses and without an illuminating system of a high positional precision, and it is also difficult to apply an adjusting step. Also the mechanical precision of the recording apparatus itself is involved, so that it has been difficult to eliminate, by mechanical adjustment only, the bandwise fluctuation resulting from the variation in the distance between the original and the scanner.
Such bandwise fluctuation appears regardless of the requested reading mode or size and becomes fatal in the optical character recognition or in the recording of the photograph size.
The object of the present invention is to achieve image reading of high quality, without unevenness.
The above-mentioned object can be attained, according to an aspect of the present invention, by an image reading apparatus comprising reading means for reading the image on an original, movement means for causing a relative movement between the reading means and the original in such a manner that the reading means executes an overlapped reading of the image on the original, setting means for setting the reading range of the reading means, and control means for controlling the overlapped reading range by the reading means according to the reading range set by the setting means.
According to an another aspect of the present invention, there is provided an image reading apparatus comprising reading means for reading the image on an original, movement means for causing a relative movement between the reading means and the original in such a manner that the reading means executes an overlapped reading of the image on the original, setting means for setting the reading color of the reading means, and control means for controlling the overlapped reading range by the reading means according to the reading color set by the setting means.
According to still another aspect of the present invention, there is provided an image reading apparatus comprising reading means for reading the image on an original in a main scanning direction with a predetermined reading width, setting means for setting the reading mode by the reading means, movement means for causing a relative movement in the main scanning direction and in the sub scanning direction between the reading means and the original, and control means for causing the reading means to read the image on the original with the predetermined reading width while causing the movement means to effect a relative movement in the sub scanning direction between the reading means and the original, then causing the movement means to effect a relative movement of an amount smaller than the predetermined reading width in the main scanning direction between the reading means and the original, and causing the reading means to read the image on the original with the predetermined reading width while causing the movement means to effect a relative movement in the sub scanning direction between the reading means and the original, wherein the control means is adapted to vary the amount of the relative movement in the main scanning direction according to the reading mode set by the setting means.
The above-described configurations allow to realize image reading of high quality without unevenness.